JPH0571370A - Intake air control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption by preventing a decrease in an engine output while reducing any pumping loss during low load running of an internal combustion engine. CONSTITUTION:An intake air control device comprises a variable valve timing device, a throttle valve 14, a bypass passage 16, an intake air regulating valve 17, an acceleration opening sensor 20, and a number of revolution sensor 21. A CPU decides an operation state by means of signals from both sensors 20 and 21 and controls the variable timing device and the intake air pressure regulating valve 17. The CPU closes the bypass passage 16 at other time than low load running to stop the feed of auxiliary air to a combustion chamber 4, and adjusts the closing timing of an intake air valve 7 to a predetermined timing. Further, during low load running, the bypass passage 16 is opened to feed auxiliary air to a combustion chamber 4 so that a pressure in an intake air pipe is reduced to a given pressure slightly lower than the atmospheric pressure. Simultaneously, the closing timing of the intake valve 7 is further delayed than a predetermined timing so as to regulate an intake air amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control device for an internal combustion engine, and more particularly to an intake control device for reducing pumping loss in the intake stroke of the internal combustion engine.

[0002]

2. Description of the Related Art In a general engine that has been conventionally used, the intake air amount is throttled by a throttle valve to adjust the air-fuel mixture amount into a combustion chamber. However, if the intake air amount is throttled by the throttle valve during the intake stroke of the engine, there is a problem that pumping loss occurs and output and fuel efficiency deteriorate.

As a solution to such a problem, for example, in Japanese Patent Laid-Open No. 56-14815, the throttle valve is not used, the intake valve is closed early at high load and the intake valve is delayed at low load. An engine is disclosed in which the amount of air-fuel mixture supplied into the combustion chamber is controlled by closing the engine. In addition, JP-A-55-1
Japanese Patent No. 28610 discloses a technique in which the throttle valve is omitted and the intake valve closing timing is advanced from the intake bottom dead center to the intake stroke side to reduce the intake air amount, as in the above technique. There is. Both of these techniques reduce the pumping loss by changing the closing timing of the intake valve and adjusting the amount of intake air into the combustion chamber.

[0004]

However, although both of the above-mentioned prior arts are effective from the viewpoint of reducing pumping loss, when the intake pipe pressure is atmospheric pressure at a low load, it is due to the following reasons. Combustion deteriorates, which is disadvantageous in terms of fuel efficiency represented by (output / loss).

That is, when the intake pipe pressure upstream of the intake valve is atmospheric pressure, the flow velocity of the air sucked into the combustion chamber is slower than in the case where the intake pressure is negative, so that the flow of fuel and air in the combustion chamber ( (Swirl flow, disturbance, etc.) becomes weak. Therefore, the flame propagation speed from ignition to combustion becomes slow, the explosive power is reduced, and the output is reduced.

Therefore, even if the pumping loss is reduced as in both the prior arts, the reduction in the output offsets the reduction in the pumping loss, and the fuel efficiency cannot be improved.

The present invention has been made in view of the above-mentioned circumstances, and an object of the invention is to provide an internal combustion engine capable of reducing the pumping loss at the time of low load and preventing the engine output from lowering to improve the fuel consumption. To provide an intake control device.

[0008]

In order to achieve the above object, the present invention, as shown in FIG. 1, shows the timing of opening and closing an intake valve for opening and closing an intake passage M2 to a combustion chamber of an internal combustion engine M1. Valve timing adjusting means M3 that adjusts according to the operating state of M1, a throttle valve M4 that is provided in the intake passage M2 upstream of the intake valve and that adjusts the amount of air to the combustion chamber of the internal combustion engine M1, Auxiliary air adjusting means M5 for supplying and stopping auxiliary air to the combustion chamber via an intake valve, and the internal combustion engine M1.
When the operating state detecting means M6 for detecting the operating state of the internal combustion engine M1 by the operating state detecting means M6 is other than a low load, the auxiliary air adjusting means M5 is controlled to supply auxiliary air to the combustion chamber. First intake control means M7 for stopping the supply and controlling the valve timing adjusting means M3 to set the closing timing of the intake valve to a predetermined timing, and the operation of the internal combustion engine M1 by the operating state detecting means M6. When the condition is low, the auxiliary air adjusting means M5 is controlled to supply the auxiliary air to the combustion chamber so that the intake pipe pressure between the intake valve and the throttle valve becomes a predetermined pressure slightly lower than the atmospheric pressure. At the same time, the valve timing adjusting means M3 is controlled to adjust the intake air amount, and the closing timing of the intake valve is set to a timing other than the above-mentioned low load. And a second intake control means M8 for changing to a different timing.

[0009]

The operating state of the internal combustion engine M1 is determined by the operating state detecting means M.
6, the first intake air control means M7 controls the auxiliary air adjusting means M5 to stop the supply of the auxiliary air to the combustion chamber and the valve timing adjusting means M3 when the operating state is other than low load. To control the closing timing of the intake valve to a predetermined timing.

When the operating state of the internal combustion engine M1 by the operating state detecting means M6 is low, the second intake control means M8 controls the auxiliary air adjusting means M5 to supply auxiliary air to the combustion chamber. At the same time, the valve timing adjusting means M3 is controlled to change the closing timing of the intake valve to a timing different from the timing at the time of the high load. Therefore, when the operating condition is low load, the throttle valve M4 is closed, but the intake pipe pressure in the intake passage M2 between the throttle valve M4 and the intake valve is a predetermined intake pipe pressure slightly lower than atmospheric pressure. become.

Therefore, when the load is low, the intake air amount into the combustion chamber is adjusted by changing the closing timing of the intake valve. Further, since the intake pipe pressure becomes a predetermined pressure slightly lower than the atmospheric pressure, pumping loss is reduced. Furthermore, at this time, the flow velocity when the air flows into the combustion chamber becomes higher than that at the atmospheric pressure.
It is believed that diffusion and mixing of fuel and intake air within the combustion chamber is promoted.

[0012]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 2 is a diagram showing a schematic structure of an intake control device for an internal combustion engine. An engine 1 as an internal combustion engine includes a piston 3 in a cylinder 2, and a combustion chamber 4 formed above the piston 3 is in communication with an intake passage 5 and an exhaust passage 6. A communication portion between the combustion chamber 4 and the intake passage 5 and a communication portion between the combustion chamber 4 and the exhaust passage 6 are opened and closed by an intake valve 7 and an exhaust valve 8 which are reciprocated by a cam shaft 9.

The engine 1 introduces a mixture of outside air from the intake passage 5 and fuel injected from the fuel injection valve 10 into the combustion chamber 4 via the intake valve 7. Then, the engine 1 explodes the air-fuel mixture in the combustion chamber 4 by the spark plug 11 to obtain a driving force, and then exhausts the exhaust gas to the exhaust passage 6 via the exhaust valve 8.

A surge tank 12 for suppressing pulsation of intake air is provided in a part of the intake passage 5, and an intake pressure sensor 13 for detecting the intake pipe pressure Pi is attached to the surge tank 12. A throttle valve 14 that is opened / closed in conjunction with the operation of an accelerator pedal (not shown) is provided upstream of the surge tank 12, and the amount of intake air to the intake passage 5 is adjusted by opening / closing the throttle valve 14. To be done. A throttle sensor 15 that detects the opening of the throttle valve 14 is provided near the throttle valve 14. Further, an accelerator opening sensor 2 for detecting an accelerator opening ACCP according to the amount of depression of the accelerator pedal.
0 is provided. This accelerator opening sensor 20
It constitutes a part of the operating state detecting means.

A throttle valve 14 is provided in the intake passage 5.
A bypass passage 16 is provided that bypasses the throttle valve 14 and connects the upstream side and the downstream side of the throttle valve 14. An intake pressure adjusting valve 17 is attached in the middle of the bypass passage 16. The intake pressure adjusting valve 17 has a linear solenoid, and the lift amount of the valve body 17a is adjusted by the linear solenoid so that the opening area of the passage is changed. In the present embodiment, the bypass passage 16 and the intake pressure adjusting valve 17 constitute auxiliary air adjusting means.
Then, the opening of the intake pressure adjusting valve 17 is controlled to adjust the amount of air (hereinafter, referred to as auxiliary air) flowing in the bypass passage 16 to supply and stop the auxiliary air to the combustion chamber 4. I am trying.

Spark plug 1 mounted on the engine 1
The ignition voltage distributed by the distributor 18 is applied to 1. The distributor 18 distributes the high voltage output from the igniter 19 to each ignition plug 11 in synchronization with the crank angle of the engine 1. The ignition timing of each ignition plug 11 is set to the ignition timing of the igniter 1.
9 is determined by the high voltage output timing. The distributor 18 includes the accelerator opening sensor 20.
A rotation speed sensor 21 that also constitutes an operating state detecting means
Is attached and detects the engine speed Ne from the rotation of the rotor of the distributor 18.

On the other hand, an oxygen sensor 22 for detecting the oxygen concentration in the exhaust gas is attached to the exhaust passage 6. A water temperature sensor 23 for detecting the temperature of the cooling water is attached to the cylinder block 1a of the engine 1.

As shown in FIGS. 2 and 3, the engine 1 is provided with a variable valve timing device 24 as valve timing adjusting means for adjusting the opening timing and closing timing of the intake valve 7. .. next,
The variable valve timing device 24 will be described in detail.

At the front end portion (left end portion in FIG. 3) of the camshaft 9, an inner case 25 having a double cylindrical shape is provided. The inner case 25 includes a boss portion 26 rotatably supported by the camshaft 9, an outer cylindrical portion 27 having a diameter larger than that of the boss portion 26, and a connecting portion 28 connecting the two. A timing pulley 29 is externally fitted and fixed to the tubular portion 27. The timing pulley 29 and a crankshaft (not shown) are drivingly connected by a timing belt 31, and the rotation of the crankshaft is transmitted to the inner case 25 via the timing belt 31.

At the front end of the camshaft 9, a bottomed cylindrical outer case 32 is fixed by a bolt 33, and the outer case 32 forms a space S between the outer case 32 and the inner case 25. In the space S, the cylindrical piston 3
4 are provided, and the inner and outer cases 25 and 32 are drivingly connected to each other by the piston 34. That is, the helical splines 34a and 34b are formed on the inner peripheral surface and the outer peripheral surface of the piston 34, and the helical splines 34a and 34b correspond to the outer peripheral surface of the boss portion 26 of the inner case 25 and the inner peripheral surface of the outer case 32, respectively. And the helical splines 26a and 32a formed in the above.

Therefore, when the rotation of the crankshaft is transmitted to the inner case 25, the inner case 25, the piston 34, the outer case 32 and the camshaft 9 are integrally driven to rotate. At this time, when the piston 34 moves in the axial direction (the left-right direction in FIG. 3), the outer case 32 and the cam shaft 9 rotate relative to the inner case 25, and the rotational phase changes.

A space S between the inner and outer cases 25 and 32 is divided into a front and a rear by a piston 34.
The front is a pressurizing chamber 35, and the rear is a spring accommodating chamber 36. An oil passage 37 is formed in the cylinder head 1b and the cam shaft 9. Then, the lubricating oil in the oil pan is sucked up by the oil pump, and the lubricating oil is supplied to the oil passage 37 based on the driving timing of the hydraulic solenoid 38. The lubricating oil thus supplied to the oil passage 37 flows into the pressurizing chamber 35 and presses the piston 34 rearward. A compression coil spring 39 is housed in the spring housing chamber 36, and the piston 3
4 is always biased forward.

Therefore, when the hydraulic solenoid 38 is turned off, the hydraulic pressure does not act on the pressurizing chamber 35, and the piston 34 is positioned on the front side as shown in FIG. 3 by the urging force of the compression coil spring 39. When the hydraulic solenoid 38 is turned on from this state, hydraulic pressure acts on the piston 34 via the pressurizing chamber 35, and the piston 34 moves backward while rotating against the biasing force of the compression coil spring 39. As a result, the phases of the inner case 25 and the outer case 32, which are drivingly connected by the helical splines 26a, 32a, 34a, 34b, shift, and the phases of rotation of the camshaft 9 and the crankshaft shift to the retard side.

A viscous coupling (viscous coupling) 41 for cushioning is provided between the outer cylindrical portion 27 of the inner case 25 and the outer periphery of the outer case 32. The viscous joint 41 includes helical splines 26a, 32a, 34a,
This is for absorbing the play in 34b and preventing the generation of abnormal noise.

As shown in FIG. 2, the intake pressure sensor 1
3, throttle sensor 15, accelerator opening sensor 20,
Rotation speed sensor 21, oxygen sensor 22 and water temperature sensor 23
Is electrically connected to an input side of an electronic control unit (hereinafter, simply referred to as “ECU”) 42. Further, each fuel injection valve 10, the intake pressure adjusting valve 17, the igniter 19, and the hydraulic solenoid 38 are electrically connected to the output side of the ECU 42.

As shown in FIG. 4, the ECU 42 includes a central processing unit (hereinafter referred to as CPU) 43 as first intake control means and second intake control means, a read-only memory (hereinafter referred to as ROM) 44, and a random number. An access memory (hereinafter referred to as RAM) 45, an external input circuit 46, and an external output circuit 47 are provided, and these are connected to each other by a bus 48. The CPU 43 executes various arithmetic processes according to a preset control program, and the ROM 4
Reference numeral 4 stores in advance a control program and initial data required for the CPU 43 to execute arithmetic processing. Also, R
The AM 45 temporarily stores the calculation result of the CPU 43.

The CPU 43 receives the intake pressure sensor 13, the throttle sensor 15, the accelerator opening sensor 20, the rotation speed sensor 21, and the oxygen sensor 22 via the external input circuit 46.
And a signal from the water temperature sensor 23. CPU43
Controls the fuel injection valve 10, the intake pressure adjusting valve 17, the igniter 19 and the hydraulic solenoid 38 connected to the external output circuit 47 based on these detection signals.

Next, the operation of the present embodiment constructed as described above will be described. The flowchart of FIG. 6 shows a valve timing control routine for controlling the closing timing of the intake valve 7 among the processes executed by the CPU 43, which is activated by a regular interrupt every predetermined time. Further, FIG. 8 shows an auxiliary air supply control routine for supplying and stopping the auxiliary air to the combustion chamber 4, which is started at every crank angle of 360 °.

First, the valve timing control routine of FIG. 6 will be described. When the CPU 43 shifts to this processing routine, in step 101 the accelerator opening sensor 20
Read the accelerator opening ACCP by step 10
At 2, the engine speed Ne is read by the speed sensor 21. Then, the CPU 43 determines whether or not the operating state at that time is in a region where the variable valve timing device 24 is operated. This determination is performed with reference to a map having the engine speed Ne and the accelerator opening ACCP as parameters as shown in FIG. In this map, an area (low load area) in which the engine speed Ne is lower than the predetermined speed Nei and the accelerator opening ACCP is smaller than the predetermined opening ACCPi is the first area Z1, and the other areas are the second areas. It is set as the area Z2.

If the operating state at that time belongs to the second zone Z2 in FIG. 5 in step 103, the CPU 43 determines that it is in the zone where the variable valve timing device 24 is not operated, and in step 104 the hydraulic solenoid 38.
It outputs a control signal for turning off. Then, Fig. 3
As shown by, the hydraulic pressure does not act on the pressurizing chamber 35, and the piston 34 is positioned on the front side by the urging force of the compression coil spring 39. At this time, as shown by the chain double-dashed line in FIG. 7, the opening timing and the closing timing of the intake valve 7 are early, and the valve rising period after the intake bottom dead center is small.

On the other hand, if the operating state at that time belongs to the first zone Z1 of FIG. 5 in step 103, the CPU 43 determines that it is in the zone for operating the variable valve timing device 24, and in step 105 the hydraulic solenoid. Three
A control signal for turning on 8 is output. Then, hydraulic pressure acts on the piston 34 via the pressurizing chamber 35, and the piston 34 moves backward while rotating against the biasing force of the compression coil spring 39. As a result, the camshaft 9 relatively rotates toward the retard angle side, the valve opening timing and the valve closing timing of the intake valve 7 are both delayed as shown by the solid line in FIG. 7, and the valve rising period after intake bottom dead center is large. Become.

As described above, when the operating state of the engine 1 is in the low load region (first region Z1), the intake valve 7 is closed later than when it is in the other region (second region Z2). The intake air once sucked into the cylinder 2 is discharged to the intake side in the piston ascending stroke after the bottom dead center, and the residual air amount in the cylinder is reduced.

Next, the auxiliary air supply control routine of FIG. 8 will be described. When shifting to this processing routine, the CPU 43 reads the accelerator opening ACCP by the accelerator opening sensor 20 in step 201, and reads the engine rotation speed Ne by the rotation speed sensor 21 in step 202. Then, the CPU 43 determines in step 203 whether or not the engine speed Ne and the accelerator opening degree ACCP are in the first region Z1 in FIG.

At step 203, if the operating state belongs to the area other than the first area Z1 (second area Z2), C
In step 204, the PU 43 operates the valve body 1 of the intake pressure adjusting valve 17.
The lift amount LB of 7a is set to "0" and a control signal to the linear solenoid for fully closing the bypass passage 16 is output, and this routine is finished. Thus, the reason why the bypass passage 16 is fully closed when the operating state belongs to the second region Z2 is that the pumping loss is originally small in this region, and the auxiliary air is throttled through the bypass passage 16. This is because it is not necessary to supply it to the downstream side of the valve 14.

If the operating state belongs to the first region (low load region) Z1 in step 203, the CPU 43
Reads the intake pipe pressure Pi in the surge tank 12 by the intake pressure sensor 13 in step 205, and in step 20
At 6,207, the intake pipe pressure Pi is within a predetermined dead zone (Pa
± ΔP) is judged. However, Pa is a predetermined value and ΔP is the width of the dead zone. This dead zone is slightly below atmospheric pressure.

When the operating state belongs to the first zone Z1, the amount of depression of the accelerator pedal is small and the throttle valve 14 is fully closed or close to fully closed, so that the intake pipe pressure Pi is at atmospheric pressure. Much lower than. Then, step 206 and step 2
At 07, the intake pipe pressure Pi is the lower limit of the dead zone (Pa
-ΔP) or less, the CPU 43 determines in step 208
And the lift amount LB of the valve body 17a at that time is updated by adding a predetermined amount ΔL to the lift amount LB of the valve body 17a (LB = 0 immediately after the operating state has changed from the second region Z2 to the first region Z1). .. Then, the CPU 43 outputs a control signal to the linear solenoid required for the valve body 17a to move by the updated lift amount LB, and this routine is finished.

When the linear solenoid of the intake pressure adjusting valve 17 receives the signal, it changes the lift amount of the valve body 17a according to the signal to open the bypass passage 16 by a predetermined opening degree. Then, the intake air upstream of the throttle valve 14 is guided to the downstream of the throttle valve 14 through the bypass passage 16. Therefore, the intake pipe pressure Pi in the surge tank 12 at that time becomes higher than the intake pipe pressure Pi-1 in the previous process by the amount of the auxiliary air passing through the bypass passage 16.

On the other hand, when the intake pipe pressure Pi becomes equal to or higher than the upper limit value (Pa + ΔP) of the dead zone in step 206, the CPU 43 proceeds to step 209 and changes the lift amount LB of the valve body 17a at that time to the predetermined amount ΔL. Subtract and update the lift amount LB. And CPU43 is the valve body 1
7a outputs the control signal required for moving the lift amount LB thus updated, and this routine is ended. When the linear solenoid of the intake pressure adjusting valve 17 receives the signal,
The lift amount of the valve body 17a is changed according to the signal to close the bypass passage 16 by a predetermined opening degree.

When the intake pipe pressure Pi fluctuates due to the processing in steps 208 and 209 and the conditions in steps 206 and 207 are satisfied,
That is, the intake pipe pressure Pi at that time is equal to the dead zone (Pa
When it is within ± ΔP), the CPU 43 outputs a control signal for holding the lift amount of the valve body 17a of the intake pressure adjusting valve 17 at that time to the linear solenoid, and ends this routine. Therefore, when the operating condition of the engine 1 is low, the bypass passage 16 is opened, so that the intake pipe pressure Pi in the surge tank 12 becomes a pressure within a predetermined dead zone (Pa ± ΔP) slightly lower than the atmospheric pressure. Will be adjusted.

As described above, in this embodiment, when the engine 1 is in the operating state other than low load, the intake pressure adjusting valve 17 closes the bypass passage 16 to stop the supply of the auxiliary air to the combustion chamber 4 ( Along with step 204), the hydraulic solenoid 38 of the variable valve timing device 24 is turned off (step 104), and the closing timing of the intake valve 7 is set to a predetermined timing. When the operating condition is low, the intake pressure adjusting valve 17 is controlled to open the bypass passage 16 to supply auxiliary air to the combustion chamber 4, and the hydraulic solenoid 38 is turned on (step 105). ), The closing timing of the intake valve 7 is set to be later than when the load is not low. Therefore, when the operating condition is low, the throttle valve 1
4 is closed, the intake pipe pressure Pi downstream of the throttle valve 14 becomes a predetermined pressure slightly lower than atmospheric pressure.

Therefore, when the load is low, the intake air amount to the combustion chamber 4 is reduced by delaying the closing timing of the intake valve 7. Further, since the intake pipe pressure Pi becomes a predetermined pressure slightly lower than the atmospheric pressure, pumping loss is reduced. For the same reason, the flow velocity of air flowing into the combustion chamber 4 becomes higher than that at the atmospheric pressure, and diffusion and mixing of fuel and intake air in the combustion chamber 4 are promoted. Therefore, unlike the prior art in which the upstream side of the intake valve is at atmospheric pressure, in this embodiment, the flame propagation speed from ignition to combustion can be increased to prevent output reduction.
Therefore, the fuel efficiency represented by (output / loss) is also improved. (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 9 is a diagram showing a schematic configuration of the intake control device corresponding to FIG. 2, and FIG. 10 is a flowchart showing an auxiliary air supply control routine corresponding to FIG.

In this embodiment, as shown in FIG. 9, instead of the bypass passage 16 and the intake pressure adjusting valve 17, a throttle opening correction mechanism 49 including a step motor or the like is provided between the throttle valve 14 and the throttle sensor 15. The throttle opening correction mechanism 49 adjusts the opening of the throttle valve 14 that is interposed and opened / closed by depressing the accelerator pedal.
The difference from the first embodiment is that the correction is performed by the above method. Further, in the present embodiment, the throttle valve 14 and the throttle opening degree correction mechanism 49 constitute an auxiliary air adjusting means. The opening of the throttle valve 14 corrected by the throttle opening correction mechanism 49 is referred to as a corrected opening ΔθTH.

When the CPU 43 shifts to the processing routine of FIG. 10, the accelerator opening ACCP and the engine speed Ne are read in step 301 and step 302, respectively, and these values belong to the first region Z1 in FIG. 5 in step 303. It is determined whether or not there is. If it belongs to a region (second region Z2) other than the first region Z1, the CPU 43
In step 304, the throttle opening correction mechanism 4
A control signal for setting the corrected opening degree ΔθTH of the throttle valve 14 by “9” to “0” is output, and this routine ends.

If the operating state belongs to the first region (low load region) Z1 in step 303, the CPU 43
In step 305, the intake pipe pressure Pi is read, and in steps 306 and 307, it is determined whether or not the intake pipe pressure Pi is within a predetermined dead zone (Pa ± ΔP). When the intake pipe pressure Pi is equal to or lower than the lower limit value (Pa-ΔP) of the dead zone, the CPU 43 proceeds to step 308 and performs processing for opening the throttle valve 14 by a predetermined amount for introducing auxiliary air. That is, the correction opening Δ at that time
The correction value ΔθTH is updated by adding a predetermined value Δθ to θTH. Then, the CPU 43 causes the throttle opening correction mechanism 49
Is the corrected opening ΔθTH for which the throttle valve 14 is updated.
Then, a signal necessary to rotate the valve in the valve opening direction is output, and this routine is finished.

Then, the throttle opening correction mechanism 49 causes the throttle valve 14 to rotate by a predetermined angle. Therefore,
The amount of auxiliary air passing between the throttle valve 14 and the intake passage 5 increases by the amount that the throttle valve 14 rotates in the opening direction, and the intake pipe pressure Pi at this time is the intake pipe pressure Pi at the previous process. Higher than -1.

On the other hand, when the intake pipe pressure Pi becomes equal to or higher than the upper limit value (Pa + ΔP) of the dead zone in step 306, the CPU 43 proceeds to step 309 to perform processing for closing the throttle valve 14. That is,
The correction value ΔθTH is updated by subtracting the predetermined value Δθ from the correction opening ΔθTH at that time. Then, the CPU 43 outputs a signal necessary for the throttle opening correction mechanism 49 to rotate the throttle valve 14 in the closing direction by the updated correction opening ΔθTH, and this routine is ended.

Then, the throttle opening correction mechanism 49 causes the throttle valve 14 to rotate by a predetermined angle. Therefore,
The amount of auxiliary air passing between the throttle valve 14 and the intake passage 5 is reduced by the amount of rotation of the throttle valve 14 in the closing direction, and the intake pipe pressure Pi at this time is the intake pipe pressure Pi at the previous process. Lower than -1.

Then, if the intake pipe pressure Pi changes due to the processing in steps 308 and 309, and the conditions in steps 306 and 307 are satisfied,
That is, the intake pipe pressure Pi at that time is equal to the dead zone (Pa
When it is within ± ΔP), the CPU 43 stops the correction of the opening of the throttle valve 14 by the throttle opening correction mechanism 49, and ends this routine. Therefore, when the operating condition of the engine 1 is low, the throttle valve 14 is forcibly opened and the auxiliary air is supplied, so that the intake pipe pressure Pi in the surge tank 12 is a predetermined dead zone slightly lower than the atmospheric pressure. The pressure will be adjusted within (Pa ± ΔP).

Therefore, also in this embodiment, similarly to the first embodiment, it is possible to prevent the output from decreasing when the engine 1 has a low load and to improve the fuel consumption. The present invention is not limited to the configuration of the above-mentioned embodiment, and may be arbitrarily changed within the scope not departing from the gist of the invention, for example, as follows. (1) In both of the above embodiments, the closing timing of the intake valve 7 is delayed when the load is low, but conversely, the closing timing may be advanced. (2) When the operating state of the engine 1 belongs to the first region Z1 in FIG. 5, the closing timing of the intake valve 7 by the variable valve timing device 24 may be switched to a plurality of stages according to the operating state. Good.

[0051]

As described above in detail, according to the present invention, when the operating condition of the internal combustion engine is other than a low load, the supply of the auxiliary air to the combustion chamber is stopped and the closing timing of the intake valve is predetermined. When the operating condition is low load, the auxiliary air is supplied to the combustion chamber so that the intake pipe pressure between the intake valve and the throttle valve becomes a predetermined pressure slightly lower than the atmospheric pressure, and the intake air In order to adjust the amount, the closing timing of the intake valve is changed to a timing different from the timing when the load is other than the low load, so the pumping loss at the low load is reduced and the engine output is prevented from decreasing. It has an excellent effect of improving fuel efficiency.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a schematic configuration diagram showing an intake air control device for an internal combustion engine according to a first embodiment of the present invention.

FIG. 3 is a sectional view of a variable valve timing device in the first embodiment.

FIG. 4 is a block diagram showing a configuration of an ECU in the first embodiment.

FIG. 5 is a map used for determining whether or not the operating state of the engine is in a region in which the variable valve timing device is activated in the first embodiment.

FIG. 6 is a flowchart showing a valve timing control routine in the first embodiment.

FIG. 7 is a diagram showing a relationship between a crank angle and a valve lift amount of an intake / exhaust valve in the first embodiment.

FIG. 8 is a flowchart showing an auxiliary air supply control routine in the first embodiment.

FIG. 9 is a schematic configuration diagram showing an intake air control device for an internal combustion engine in a second embodiment of the present invention.

FIG. 10 is a flowchart showing an auxiliary air supply control routine in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 4 ... Combustion chamber, 5 ... Intake passage, 7 ... Intake valve, 14 ... Throttle valve which constitutes a part of auxiliary air adjusting means in the second embodiment, 16
... bypass passage forming a part of auxiliary air adjusting means in the first embodiment, 17 ... intake pressure adjusting valve forming a part of auxiliary air adjusting means in the first embodiment, 20 ... part of operating state detecting means Accelerator opening sensor, 21 ...
A rotation speed sensor, which constitutes a part of the driving state detecting means, 24
... a variable valve timing device as valve timing adjusting means, 43 ... a CPU constituting the first intake controlling means and the second intake controlling means, 49 ... a throttle constituting a part of the auxiliary air adjusting means in the second embodiment. Opening correction mechanism, Pi ... Intake pipe pressure

Claims (1)

[Claims] 1. A valve timing adjusting means for adjusting an opening / closing timing of an intake valve for opening / closing an intake passage to a combustion chamber of an internal combustion engine according to an operating state of the internal combustion engine, and an intake passage upstream of the intake valve. A throttle valve that is provided to adjust the amount of air to the combustion chamber of the internal combustion engine, auxiliary air adjusting means that supplies and stops auxiliary air to the combustion chamber through the intake valve, and the internal combustion engine An operating state detecting means for detecting an operating state, and when the operating state of the internal combustion engine by the operating state detecting means is other than a low load, while controlling the auxiliary air adjusting means to stop the supply of auxiliary air to the combustion chamber. A first intake control means for controlling the valve timing adjusting means to set a closing timing of the intake valve to a predetermined timing; and the operating state detecting means. When the operating condition of the internal combustion engine is low, the auxiliary air adjusting means is controlled to set the intake pipe pressure between the intake valve and the throttle valve to a predetermined pressure slightly lower than the atmospheric pressure, and the auxiliary air is supplied to the combustion chamber. And second intake control means for controlling the valve timing adjusting means to adjust the intake air amount and changing the valve closing timing of the intake valve to a timing different from the timing other than when the load is low. An intake control device for an internal combustion engine, comprising: